The present invention relates generally to a probe which facilitates delivery of cardioplegia in the coronary sinus and provides venous drainage for cardiopulmonary bypass, and more particularly to a probe which can be placed around the coronary sinus under direct visualization.
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Narrowing or blockage of the coronary arteries often results in myocardial ischemia and infarction. Different approaches have been developed for treating coronary artery disease, including balloon angioplasty, atherectomy, laser ablation, stents, and coronary artery bypass grafting surgery. Excellent long-term results have been achieved with conventional coronary bypass surgery. However, significant mortality and morbidity still exist due to the use of cardiopulmonary bypass for circulatory support and the traditional method of access by median sternotomy.
Minimally invasive concepts have been adopted in cardiac surgery to make coronary revascularization less invasive. In the port-access approach, a cardiac procedure is performed through minimal access incisions often made between a patient""s intercostal space and cardiopulmonary support is instituted through an extra-thoracic approach.
In both conventional and minimally invasive coronary artery bypass grafting surgeries, and other cardiac surgeries such as heart valve repair or replacement, septal defect repair, pulmonary thrombectomy, atherectomy, aneurysm repair, aortic dissection repair and correction of congenital defects, cardiopulmonary bypass and cardiac arrest are often required. In order to arrest the heart, the heart and coronary arteries must be isolated from the peripheral vascular system, so that cardioplegia solution can be infused to paralyze the heart without paralyzing the peripheral organs. Cardiopulmonary bypass is then initiated to maintain peripheral circulation of oxygenated blood.
In conventional coronary artery bypass surgery, cardioplegia solution is usually administered through a catheter inserted into the aorta. Problems associated with this approach are that an additional wound site is generally required for administering cardioplegia, and that a cardioplegia catheter, located in the vicinity of the surgical field, may interfere with a surgeon""s operation. Retrograde administration of cardioplegia to the coronary sinus as an alternative approach has been shown to be beneficial to the heart. In minimally invasive coronary artery bypass surgery, placement of a cardioplegia catheter often requires fluoroscopic guidance, and circulatory isolation of the heart and coronary blood vessels generally involves insertion of multiple large catheters in either the neck, or the groin, or both to remove blood from the superior vena cava and inferior vena cava for cardiopulmonary bypass. Problems with this procedure are that excess catheterization and use of fluoroscopy may be associated with increased morbidity.
New devices and methods are therefore desired for isolating the heart and coronary blood vessels from the peripheral vascular system and arresting cardiac function, particularly devices which do not require multiple cannulation sites, fluoroscopy, and/or additional cardioplegia catheter insertion.
The present invention provides a cardioplegia access view probe having the ability to deliver cardioplegia solution to the coronary sinus and drain venous blood for cardiopulmonary bypass. The probe further has the ability to provide direct visualization of the right atrium and coronary sinus for placement of a cardioplegia catheter. The cardioplegia access view probe comprises an elongate tubular member having a proximal end, a distal end, and a lumen therebetween. In a preferred embodiment, a toroidal balloon is attached to the distal end of the tubular member, which comprises a balloon inflation lumen.
The lumen of the tubular member is partitioned into a distal and a proximal segment by a membrane mounted within the lumen. The membrane can be removable or can be punctured by a cardioplegia catheter. A vacuum port in communication with the distal segment of the tubular member extends proximally and is operable from the proximal end of the probe. The tubular member may further include one or more drainage ports for draining venous blood from the right atrium. Deoxygenated blood may be delivered to a bypass-oxygenator machine through the proximal end of the tubular member, which is adapted for attachment to the bypass-oxygenator machine. The probe may also include a fiberoptic light source and a diffuser at its distal end to assist a surgeon in visualizing the right atrium and coronary sinus for placement of a cardioplegia catheter.
In an alternative embodiment, instead of having a toroidal balloon at the distal end of the tubular member and a vacuum port, the distal end of the tubular member has a recess vacuum manifold, which extends circumferentially around the distal end of the tubular member and communicates with a vacuum port. This design simplifies construction of the probe by eliminating the toroidal balloon and its inflation lumen and port.
The present invention also provides methods for administering cardioplegia to the coronary sinus of the heart. The methods employ a cardioplegia access view probe as described above. According to one method, the distal end of the probe is inserted into the right atrial chamber after an incision is made in the right atrium. The distal end of the probe is positioned around the coronary sinus with the assistance of a fiberoptic light source included in the probe. A vacuum is then applied to the vacuum port to remove fluid, blood, or air around the coronary sinus. In the embodiment which includes a toroidal balloon, the balloon is inflated to provide stabilization of the probe and a seal around the coronary sinus when vacuum is applied.
To insert a cardioplegia catheter into the coronary sinus, the membrane is removed from the tubular member by pulling an attachment or other mechanism at the proximal end of the tubular member. Alternatively, the membrane, which may include at least one perforation line, can be punctured by a cardioplegia catheter. Either method allows a surgeon to visualize the coronary sinus directly for positioning the cardioplegia catheter without the need for fluoroscopy.
After placement of the cardioplegia catheter, cardioplegia solution can be delivered to the coronary sinus. Vacuum is removed, and the toroidal balloon or vacuum manifold is lifted from the atrial tissue. Venous blood can then be drained through the lumen of the probe and venous drainage ports optionally included in the elongate tubular member to a bypass-oxygenator machine to provide circulatory isolation of the heart and coronary blood vessels from the peripheral vascular system.
It will be understood that there are many advantages to using a cardioplegia access view probe as disclosed herein. For example, the probe of the invention provides (1) direct visualization of the right atrium and coronary sinus, obviating the need for fluoroscopy, (2) venous drainage for cardiopulmonary bypass, obviating the need for multiple cannulation sites, (3) a light source to illuminate the right atrium to assist in placement of a coronary sinus catheter, (4) a vacuum/vent to clear the view between the window and heart structure, (5) a simple method for administering retrograde cardioplegia via the coronary sinus, and (6) devices adapted for minimally invasive procedures.